Non-densified silicon nitride beta-phase material

Claim 1

A silicon nitride beta-phase material comprising a structure of beta-phase silicon nitride crystals and at least one nitriding agent having a bulk density of less than about 3.2 g/cm 3 , an apparent porosity of at least about 10%, and less than 10 weight percent alpha-phase silicon nitride without any significant amounts of densification aids made by (a) comminuting a slurry including a mixture consisting essentially of (i) silicon-containing powder, (ii) water, and (iii) at least one nitriding agent, said comminuting being performed to form non-oxidized surfaces on the silicon powder and to allow chemical reaction between the silicon and the water; (b) reducing the water content of the reacted slurry to a degree sufficient to form a resultant dry mass; (c) nitriding the dry mass by exposure to a nitriding gas including at least nitrogen to form a mass of substantially alpha-phase silicon nitride; and (d) converting the resultant silicon nitride mass at a conversion temperature of from about 1450° C. to about 2100° C. for a sufficient length of time to convert the silicon nitride from an alpha-phase material to a beta-phase material having at least one nitriding agent.